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222             MOEPHOLOGY AND EVOLUTION
-J.J
from the left side of the body of the first lumbar vertebra to the right iliac fossa. In the large intestine there is no mesentery to the csecurn, ascending, descending and pelvic colons. The appendix has a mesentery, but no other part has such a long mesentery as the iliac colon. In the rectum the peritoneum is disposed as in Man, being first surrounded by it, and then the peritoneum gradually leaves it till the lower part and the anal canal are quite devoid of a serous investment.
The other Apes have similar conditions. In lower Primates, which are pronograde, the colon is suspended on a complete mesentery ; and the binding down of parts of it in the higher Apes is part of the changes which accompany the erect attitude.
The Salivary Glands.
THE CHIMPANZEE.
Many labial salivary glands are present.
The parotid gland (fig. 27) is pyramidal in shape, with the base upwards, immediately below the concha auris. The apex curves round the angle of the mandible and touches the submaxillary gland. The upper part is composed of small lobules, but the lower part is coarse. The capsule is well marked, but no lymphatic glands are included within it. Stensen's duct emerges from the upper part of the gland and its course and relations are as in Man. The relations of the gland to the large vessels and nerves are also as in Man.
The submaxillary gland (fig. 31) is fiat and triangular and measures 1^ in. in diameter. It is partly under the horizontal rarnus of the mandible and partly on the inter-